EP1159174B1 - System for regulating the stability of a motor vehicle - Google Patents

Description

Background of the Invention

The present invention relates to a vehicle stability control system for land vehicles, with a yaw rate sensor that in operation a representative of the yaw rate of the vehicle delivers the first output signal. With such yaw sensors the yaw rate is used as a measure of the dynamic behavior of the vehicle and for generating an intervention signal used by an electronic control unit.

State of the art

There is now the problem with known arrangements that before especially during the warm-up phase the output signal of the rotation rate sensor a very strong zero position drift caused by Exhibits temperature fluctuations. To avoid through the Misalignments caused in the zero position drift will occur in the EP 0 893 320 A2 proposed a vehicle control device, according to when the discrepancy between the means of the Yaw rate sensor and one of the vehicle speed and the steering angle estimated yaw rate exceeds a threshold value, at least one wheel braked becomes a yaw moment to reduce the yaw rate deviation generate in the vehicle body, the vehicle control device temporarily increases the threshold until the Yaw rate sensor is warmed up.

The vehicle control device known from EP 0 893 320 A2 has the disadvantage that safety-critical driving conditions are not can be completely excluded, as an automatic Brake intervention triggered to reduce the yaw rate deviation becomes. As a trigger criterion for automatic brake intervention is an estimated yaw rate used, which inevitably not a particularly reliable Represents size. Another disadvantage is that the performance the vehicle control device in one Insignificant dimensions is limited because during the warm-up phase the threshold is increased, which increases the response becomes sluggish. Furthermore, these are known Vehicle control device temperature fluctuations occurring during operation not considered.

DE 43 40 719 A1 describes a circuit arrangement for evaluation which reveals signals from a yaw rate sensor, where the temperature dependence of the signals of the Yaw rate sensor using an additional one Temperature sensor is compensated. For this, the Temperature sensor the temperature of the yaw rate sensor recorded and a correction factor for each temperature determined determined for the signals of the yaw rate sensor and saved. On the one hand, the temperature sensor can have a temperature-dependent characteristic and on the other hand the relationship between a determined temperature of the yaw rate sensor and the temperature-dependent Change of a corresponding signal of the yaw rate sensor can vary, can be reliable Compensation for temperature-dependent changes in the Yaw rate sensor signals not guaranteed become. Furthermore, this circuit arrangement requires an additional one Sensor, namely the temperature sensor.

Problem underlying the invention

The invention is therefore based on the object of a method to compensate the zero position drift of a rotation rate sensor to create that neither on security nor has adverse effects on performance.

Solution according to the invention

To solve this problem, the invention proposes a device according to claim 1 and a method according to claim 6 before.

The invention is based on the finding that yaw rate sensors very strongly temperature-dependent output signals deliver. Since the rotation rate sensors are usually in the passenger compartment or be housed in the engine compartment of the vehicle, they are exposed to particularly strong temperature fluctuations. These can be of the order of 60 ° C if the Rotation rate sensor during vehicle downtimes in winter extremely low or extremely high in summer, those in vehicle operation by the heating or the Air conditioning system increased or reduced to room temperature again become. In this respect, the method according to the invention is preferred here apply.

But it is also understood that the manner of the Invention also gained knowledge of the temperature for others Applications can be used in the vehicle, for example to control the heating or air conditioning. Especially Such applications are simply possible when using a Bus system in the vehicle, e.g. CAN bus, on the vibration frequency output signal of the rotation rate sensor can be accessed.

The yaw rate sensor delivers a (first) output signal, the a current yaw rate of the vehicle, falsified by the Operating or ambient temperature of the yaw rate sensor reproduces. The problem here is that the temperature dependencies of the output signals even for different yaw rate sensors of the same type and series differ greatly can deviate (see Fig. 1), so that a fixed (programmed or hardwired) logic for Temperature compensation usually fails. You can also Age-related fluctuations also not in this way be balanced. The yaw rate sensor also delivers a (second) output signal, which is a (frequency or voltage) signal that would actually be constant, but also by the operating or ambient temperature according to a known law, preferably linearly changed is (see Fig. 2).

Incidentally, in modern vehicles with ABS, ASR, etc. There are a number of sensors that provide output signals which are used to determine the yaw rate could (steering angle sensor, wheel speed sensors etc.). Indeed these output signals are only for a very rough one Estimation or determination of non-zero yaw rates suitable. To see that a yaw rate of zero or practically zero (within a predetermined tolerance band) the output signals of such sensors can, however with very good and reliable results become.

The invention makes use of these findings.
The control program for the computer unit differentiates between a learning mode and an operating mode.

In the learning mode, the regularity is determined according to the the zero point of the detected by the yaw rate sensor Yaw rate of the vehicle depending on the operating or Ambient temperature shifts. This is done for different occurring operating or ambient temperatures of the yaw rate sensor, as they come from the second output signal can be determined, then the current yaw rate is determined, if the output signal of the further sensor (for example the wheel speed sensors or the steering angle sensor or the Fact that the automatic gear selector lever is in "park") can be seen that the yaw rate of the vehicle is zero or is practically zero.

The so determined (due to the influence of temperature) of zero deviating yaw rate is dependent as the zero offset value of the respective operating or ambient temperature the yaw rate sensor entered in a table, which is kept in the data memory as a so-called lookup table. The respective operating or ambient temperature is used of the yaw rate sensor as the addressing criterion of the lookup table.

During the operating mode, the yaw rate sensor detected yaw rate of the vehicle with a zero offset value corrected that depending on the particular Operating or ambient temperature of the yaw rate sensor (corresponding to the second output signal) from the table is read out. The value corrected in this way serves as the basis for a control signal for an intervention in driving behavior of the vehicle, for example for selective actuation one or more wheel brakes, limitation or reduction the throttle valve position, unfolding a support wheel or the like.

Advantageous further training

In a preferred embodiment, the yaw rate sensor by a micromechanical vibration gyrometer, and / or the further sensor arrangement by the wheel speed sensors for the ABS / ASR brake system, a steering angle sensor or the like., and / or the writable data storage formed a non-volatile read / write memory.

The learning mode is preferably determined by determining a gradient of neighboring temperature-related zero offset values and comparison of a current zero offset value with that resulting from the gradient course theoretical value the current zero offset value before writing to the data memory for plausibility checked.

In learning mode, you can also interpolate between zero offset values already determined in the database missing zero offset values are added.

In addition, in the learning mode by comparing one already determined zero offset value with a current Zero offset value for the same or almost the same Temperature value, and replacement of the already determined zero offset value by a current zero offset value in the data memory if they differ from each other due to aging Zero offsets can be compensated.

In the learning mode, a first temperature-related zero offset value can be set during final assembly with the vehicle at a standstill and predetermined ambient temperature in the data storage be registered.

The first output signal is preferably in the operating mode corrected with a zero offset value that depends from the respective second output signal from the data memory is read out.

The second output signal is preferably the oscillation frequency of the yaw rate sensor because the oscillation frequency of the yaw rate sensor (GRS) with the operating or ambient temperature of the Yaw rate sensor (GRS) is correlated. This allows a delay free and direct compensation of the zero offset.

Brief description of the drawings

Fig. 1

eine schematische Darstellung von Kurvenverläufen der Nullpunkt-Versatz-Werte dreier Gierratensensoren in Abhängigkeit von der Temperatur;

Fig. 2

eine schematische Darstellung des Kurvenverlaufs des zweiten Ausgangssignals des Gierratensensors in Abhängigkeit von der Temperatur; und

Fig. 3

ein schematisches Blockschaltbild einer erfindungsgemäßen Fahrzeugstabilitätsregelsystems.

Further properties, advantages, features and possible variations of the invention are explained on the basis of the following description of a currently preferred embodiment of the invention with reference to the drawings. Show this

Fig. 1

a schematic representation of curves of the zero offset values of three yaw rate sensors as a function of temperature;

Fig. 2

a schematic representation of the curve of the second output signal of the yaw rate sensor as a function of the temperature; and

Fig. 3

a schematic block diagram of a vehicle stability control system according to the invention.

Detailed description of the embodiments

3 shows a vehicle stability control system for land vehicles, especially motor vehicles. The vehicle stability control system has an electronic control unit ECU, the one computing unit CPU and at least one writable Data memory RAM and a control program memory ROM has, which are connected to the computing unit CPU. With The electronic control unit ECU is a yaw rate sensor GRS connected in the form of a micromechanical vibrating gyrometer, the one in operation for the yaw rate of the vehicle representative first output signal GR delivers and one for the operating or ambient temperature of the yaw rate sensor GRS provides a representative second output signal Temp. The Both output signals GR and Temp are in the electronic Control unit ECU fed where it through the computing unit CPU by means of a stored in the program memory ROM Program are processed.

It is understood that the two memories RAM, ROM too non-volatile, battery-buffered FLASH RAMs or EEPROMs could be.

Furthermore, ECU is in the electronic control unit Output signal O-GR fed to a further sensor arrangement SENS, the non-yaw of the vehicle at least within represent a predetermined tolerance band. This sensor arrangement SENS can the wheel speed sensors for the ABS / ASR brake system, a steering angle sensor or the like for straight-ahead travel or vehicle standstill detection his. Possibly. it is required by each Sensors delivered signals through suitable processing or linkage to evaluate that a definitive "Non-yaw" of the vehicle safely reproduced and recognizable is.

The electronic control unit ECU generates in the following described a control signal for an automatic Brake intervention so the driving behavior of the vehicle to influence.

The control program for the computing unit CPU is in one Learning mode and an operating mode divided.

In the learning mode, the computer unit calculates CPU if it is present of the output signal O-GR of the further sensor SENS, which indicates that the motor vehicle is currently not its The vertical axis rotates (yaws) one from the first output signal temperature-related zero offset value depending from the second output signal Temp. The zero offset value determined in this way is with the respective temperature value as Stores the address index in the data memory RAM. This approach is repeated again and again when the motor vehicle not yaw and also an operating or ambient temperature of the yaw rate sensor is present for which still no zero offset value was determined.

The learning mode is also determined by determining a gradient of neighboring temperature-related zero offset values and comparison of a current zero offset value with the theoretical resulting from the gradient Value the current zero point offset value before writing checked for plausibility in the data memory.

If certain for operating or ambient temperatures of the Yaw rate sensor no zero offset value in the data memory can be obtained by interpolating between zero offset values already determined in the database missing zero offset values are added.

By comparing an already determined zero offset value with a current zero offset value for the same or almost the same temperature value, and replace of the zero offset value already determined by a current zero offset value in the data memory age-related zero point offsets compensated.

A first temperature-related zero offset value is created in the final assembly with the vehicle stationary and predetermined Ambient temperature written into the data memory.

In the operating mode, the computer unit reads from the data memory taking into account the second output signal temperature-related zero offset value and subtracted this from the current first output signal a brake system control signal for an intervention in the Generate driving behavior of the vehicle.

Claims (10)

1. Device for regulating the stability of vehicles for land vehicles, comprising:

   an electronic control unit (ECU) for receiving a first, a second and a third output signal (GR, Temp, O-GR),

   a yaw rate sensor (GRS) for delivering the first output signal (GR), which represents a yaw rate of the vehicle,

   wherein the second output signal (Temp) represents the operating or ambient temperature of the yaw rate sensor, and

   a sensor arrangement (SENS) for delivering the third output signal (O-GR), which represents a non-yawing state of the vehicle, wherein the electronic control unit

   in a learning mode determines a temperature-related zero offset value from the first output signal in accordance with the second output signal and stores it in a data memory (RAM) if the third output signal indicates a non-yawing state of the vehicle,

   in an operating mode reads a temperature-related zero offset value out of the data memory in accordance with the second output signal and corrects the first output signal with this zero offset value in order to generate a control signal for controlling the road behaviour of the vehicle,

   characterised in that

   the second output signal is a frequency or voltage signal of the yaw rate sensor varied by the operating or ambient temperature according to a known regularity.
2. Device according to Claim 1,
   characterised in that

   the second output signal is the oscillation frequency of the yaw rate sensor which is correlated with the operating or ambient temperature of the yaw rate sensor.
3. Device according to Claim 1 or 2,
   characterised in that

   the electronic control unit stores the determined zero offset value in the data memory if a comparison of the determined zero offset value with a theoretical zero offset value resulting from a gradient of adjacent temperature-related zero offset values stored in the data memory for checking the plausibility of the determined zero offset value has been successfully concluded.
4. Device according to any one of Claims 1 to 3,
   characterised in that

   the electronic control unit adds zero offset values missing from the data memory by interpolating between zero offset values already stored in the data memory.
5. Device according to any one of Claims 1 to 4,
   characterised in that

   the data memory contains a first temperature-related zero offset value which represents a zero offset value at the final assembly stage with the vehicle at a standstill and a predetermined operating and ambient temperature of the yaw rate sensor.
6. Method for regulating the stability of vehicles for land vehicles, comprising the following steps:

   delivering a first output signal (GR) by means of a yaw rate sensor (GRS) which represents a yaw rate of the vehicle,

   delivering a second output signal (Temp) which represents an operating or ambient temperature of the yaw rate sensor,

   delivering a third output signal (O-GR) by means of a sensor arrangement (SENS) which represents a non-yawing state of the vehicle,

   detecting the first, the second and the third output signal by means of an electronic control unit (ECU),

   in a learning mode determining a temperature-related zero offset value from the first output signal in accordance with the second output signal and storing the temperature-related zero offset value in a data memory (RAM) if the third output signal indicates a non-yawing state of the vehicle, and

   in an operating mode reading a temperature-related zero offset value out of the data memory, taking account of the second output signal, and correcting the first output signal with the zero offset value which is read out in order to generate a control signal for controlling the road behaviour of the vehicle,

   characterised in that

   a frequency or voltage signal varied by the operating or ambient temperature according to a known regularity is delivered by the yaw rate sensor as second output signal.
7. Method according to Claim 6,
   characterised in that

   the second output signal is delivered as the oscillation frequency of the yaw rate sensor, wherein the oscillation frequency is correlated with the operating or ambient temperature of the yaw rate sensor.
8. Method according to Claim 6 or 7,
   characterised in that

   the storage of the determined zero offset value comprises the following steps:

   determining a gradient of adjacent temperature-related zero offset values stored in the data memory,

   comparing the determined zero offset value with a theoretical zero offset value resulting from the determined gradient in order to check the plausibility of the determined zero offset value, and

   storing the determined zero offset value if the plausibility check has been successfully concluded.
9. Method according to one Claims 6 to 8,
   characterised in that
   the determination of temperature-related zero offset values in the learning mode comprises the following steps:

   interpolating between zero offset values stored in the data memory, and

   storing zero offset values missing from the data memory by interpolating determined zero offset values.
10. Method according to one Claims 6 to 9,
    characterised in that the determination of the zero offset values in the learning mode comprises the following steps:

    determining a first temperature-related zero offset value at the final assembly stage with the vehicle at a standstill and a predetermined operating or ambient temperature of the yaw rate sensor, and

    storing the first temperature-related zero offset value in the data memory.

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